Lighting equipment designed for illuminating office-like interiors is often categorized by how it is mounted. Some products are recessed within the ceiling structure and others are suspended from the ceiling structure. One common ceiling type is a suspended grid system with lay-in acoustic tile. Lighting fixtures are recessed within the ceiling and emit light downwardly into the surrounding space. These systems are called “direct lighting” systems because they provide illumination directly to the surfaces within the architectural spaces below.
Suspended general illumination lighting equipment typically emits most of its light upward so as to light the ceiling from which the luminaires are suspended. In this approach, the architectural space is indirectly illuminated by light reflected off the ceiling. Hence, this approach is referred to as “indirect lighting.” Some of this type of equipment also provides a component of downward emission and therefore is sometimes called “indirect-direct lighting” or “direct-indirect lighting”—though it is generally still categorized as “indirect lighting.”